A conventional image coding device is constructed in such a way as to, when compression-coding a certain picture sequence, carry out prediction coding using a spatial correlation or a temporal correlation in the picture sequence, thereby improve the compression efficiency. On the other hand, because a large number of video streams compressed are managed in recording space having a huge size in a digital recording device with a built-in HDD, a cloud type system, and so on which have been provided in recent years, the frequency of occurrence of a state in which different picture sequences have similar video contents increases depending upon conditions.
Under such a state, further data compression can be carried out by also utilizing a correlation which exists between different picture sequences. The following patent reference 1 discloses a technology of recording a plurality of recorded programs with a high degree of compression efficiency by making a comparison among several different recorded programs in a digital recording device with a built-in HDD, and compression-coding difference information acquired on the basis of the results of the comparison.